This set of go bowls was acquired from an antique store in Kanagawa.
They are a gorgeous dark color and very dense. The wood is absolutely in the ebony/rosewood family. It is very similar to 'black persimmon.' Bowls like this can be purchased new from shops like Miwagobanten for about $800 plus shipping:
I would call Ebony bowls top-tier, alongside woods like Mulberry and Black Persimmon. Black persimmon (about $2000 new) is very similar to Ebony, but generally has more of a tan tone interspersed with the black lines - but that may depend on the grain of each trunk - for example, here are a couple videos of Yoshihiro Sasada cutting black persimmons in his workshop.
I'm not sure that Mr. Sasada has ever cut an ebony tree, but he has made veneers:
In 2017, CITES barred the shipment of rosewood-family products over 10kg, but that was relaxed in November 2019. In any case the bowls together weigh under 2kg so it is not an issue.
The bowls are 16cm wide and 10.3cm tall. XL bowls are usually about 14.5cm wide, so I think these are XXL and should fit go stones of any size.
I can discount the price slightly if you insist on Seamail shipping, but I would not suggest it for an item this valuable. I can also bundle this item with other items if you would like to combine shipping.
International Express shipping from Japan (to almost everywhere) is already included in the purchase price for free. After purchase, please allow a week for packing and Customs, then you will get a FedEx tracking number and delivery in 5 business days.
Please understand that this is a vintage item, so it is sold in an as-is condition.